JPH0245476B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for introducing needle thread to be wound onto a bobbin of a lockstitch sewing machine into a slot in a bobbin case which extends to a thread tension device.

U.S. Patent No. 3,693,566 to Singer Company, dated September 26, 1972, describes a bobbin replenishment mechanism for a lockstitch sewing machine. This mechanism has thread-engaging fingers adapted to guide the needle thread to be wound onto the bobbin into a bobbin case slot leading to a thread tension device. The thread is moved along said fingers and the captured thread loop is transferred into said slot as it is moved around the bobbin by a thread taker, and the thread taker rotates further. At times, the thread is moved downwardly through the slot into the thread tension device. However, after the thread has been released from the fingers, it is often the case that the thread is pulled out of the mouth of the slot and begins to move across the slot. Therefore, the thread cannot enter the thread tension device and winding of the thread onto the bobbin is prevented.

It is an object of the present invention that the bobbin replenishment mechanism controls the movement of the needle thread carried by the thread taker and introduces this thread completely into the bobbin case slot leading to the thread tension device, and The purpose is to enable the thread to be moved to the thread tension device.

Another object of the present invention is to provide a bobbin winding mechanism with a thread guide finger so that the leg of the thread loop of the needle thread carried by the thread take-up device is arranged so that the thread passes through the slot in the bobbin case. To provide a mechanism for holding the bobbin case around the bobbin case until it is securely inserted into the tensioner.

Other objects and advantages of the invention will become apparent from the embodiments of the invention described below with reference to the accompanying drawings.

According to the present invention, the lockstitch sewing machine is a cup-shaped thread taker that moves in a circular motion and has a peripheral rim in which a thread catching tip is formed and an axis;
a non-rotating bobbin case supported within the thread taker;
A rotatable bobbin housed inside the bobbin case, a needle capable of reciprocating in the vertical direction and movable to a position for giving a loop of needle thread to the thread catching tip for catching, and a bobbin case. A thread tensioning device is carried by the thread tensioning device with an arm which together with the shoulder on the bobbin case forms a thread slot for the device, and one foot of the loop in which the needle thread is captured is connected to the slot. a finger piece for guiding into and from the thread tension device;
A thread catching groove that extends from the outer periphery of the top flange of the bobbin to a hub extending between the top flange and the bottom flange of the bobbin, and a thread catching groove that rotates the bobbin, passes through the thread tension device, and captures the thread that extends onto the bobbin. a device for catching and winding the bobbin with a groove, the groove communicating the inside of the bobbin case housing the bobbin with the outer periphery of the bobbin case through which the needle thread slides during normal lockstitch operation; , the finger has a thread-engaging edge, the thread-engaging edge having a circularly curved portion at the distal end of the finger proximate to the slot, and an introduction portion extending straight in contact with the curved portion. The introduction part introduces the thread into the curved part until the thread held at the tip crosses a line perpendicular to the radius extending from the axis of the thread taker to the tip of the finger piece. A lockstitch sewing machine is provided that holds the

In the figure, reference numeral 10 indicates a portion of the sewing machine bed, which has an upwardly open cavity 12.
, in which a thread remover 14 is fitted so as to be rotated by a hollow shaft 15 . The thread taker works in conjunction with a needle 16 that reciprocates in the longitudinal direction, as described in Stanley J., September 26, 1971.
Lockstitching is performed as described in Ketterer, U.S. Pat.

As shown, the thread taker 14 is in the form of a cup with an open top. The thread taker has a rim 18 and an inwardly projecting annular shoulder 20, which shoulder has a transverse hole 2.
4 forms a needle thread ring catching point 22.

The bobbin case 26 is received within the cup shape of the thread taker and the bobbin case bearing flange 28
is adapted to rest against the shoulder 20 of the thread remover. The bobbin case is formed with an upwardly opening bobbin-compatible cavity 30 with a large central hole 31 extending through the bottom of the cavity.

The bobbin case 26 carries a thread tension device 32,
The device has a supporting arm 33, a downwardly bent arm 34
and a thread tension spring 36, which thread tension spring is connected to the downwardly bent arm 34 by a screw 38.
is installed on. A screw 40 extending through the support arm 33 attaches the thread tension device to the bobbin case. A slot 42 in the form of a U-ring is formed in the spring 36 and is adapted to separate tongues 44 through which the screw 38 and arm 34 can be inserted.
Upper locating pin 46 extends. The tongue 44 is surrounded by another spring plate portion 48 which frictionally engages the thread in the thread tension device 32 with said downwardly bent arm 34 and applies a tension force to the thread. I'm starting to add more. The downwardly bent arm 34 is formed with a slot 50 for receiving the thread, the end of which has a small hole 52 as shown in FIGS. It is adapted to guide the section 48.

The member 58, which is seated in a shallow recess in the bobbin case flange 28 and is attached to the sewing machine by screws 60, is attached to the sewing machine when the bobbin case 26 is attached to the sewing machine bed 1.
This is to prevent rotation within zero. A pressing spring arm 62 extending from a base plate 64 mounted on the bed, and a base plate 70 mounted on the bed.
A rotation restraining lip 66 on an arm 68 extending from provides additional restraint on the bobbin case.

The bobbin 72 is freely rotatable within the bobbin fitting cavity 30 of the bobbin case 26. The bobbin has a top flange 74 formed with an outwardly extending slot 76 that is slightly offset from its true radial position on the top flange. The bobbin is also a pull-up boss 80
The boss fits into the central hole 31 of the bobbin case. A non-circular hole 82 is formed in the boss 80 and is adapted to mate with a non-circular end 84 of a drive spindle 85 located within the hollow fiber threader shaft 15 .
A smooth cylindrical hub 86 is provided between the flanges 74, 78 of the bobbin. Said spindle forms part of the bobbin thread replenishment mechanism described in Stanley J. Ketterer, U.S. Pat. . The mechanism has a control arm 88;
The arm is positioned away from the bobbin case as described in the patent (FIG. 1) and in FIGS. 4 and 5.
As shown in Figures 6, 7, 8 and 9, it is movable between the bobbin case and the position above the bobbin. Arm 88 as described in U.S. Pat. No. 3,695,566.
is above the bobbin case and bobbin, the spindle 85 rises and enters the hole 82 in the bobbin, so that the bobbin is rotated together with the thread taker to wind the needle thread T onto the bobbin. Become. In the position of the control arm 88 when winding the bobbin, the fingers 90 on the arm hold the tip end 91 of the control arm 88,
It projects below the end 92 of the thread tension device support arm 33 in close proximity to a slot 94 between the end and a shoulder 96 on the bobbin case.

When the bobbin winding operation is performed, as shown in FIG.
After the thread is caught by the thread looper, the finger piece 90 is passed around the bobbin case (Fig. 4) by the thread taker.
and one leg 98 of the thread ring
is moved over the bobbin case and the other leg 99 is moved under the bobbin case (FIG. 5). Legs 98 are engaged with edges 100 of fingers 90 as shown in FIG. This thread leg 98 is guided into the slot 94 by fingers 90. As will be explained in more detail below, the edge 100 of the finger is shaped to retard the movement of the thread thereon, thus preventing the thread from coming off the finger prematurely and being pulled out of the mouth of the slot 94. and forms a loop over the end 92 of the support arm 32, which serves to prevent threads from passing through the slot 94. thread leg 98
After the thread enters the slot 94, further rotation of the thread taker moves the thread to the position shown in FIG. Enter the small hole 52. At this stage, the needle thread is introduced between said downwardly bent arm 34 and the spring plate portion 48 of the thread tension device.

If the thread taker rotates further, the thread loop of the needle thread will come off the tip 22 of the thread taker and the spindle 85 will be removed.
According to the position the bobbin occupies when the bobbin is lifted, the slot 76 in the bobbin top flange
As shown in the figure, from the small hole 52 the bobbin 72
and is moved past the free end of the loop of needle thread extending into the needle hole 102 in the needle plate 104. As the thread taker rotates further, the leg of needle thread that has entered the bobbin through the slot is wound around the bobbin hub 86. When winding of the thread begins, the slack in the thread disappears and the thread is drawn into the groove 106 of the thread tension device. The slots 76 are offset so that the thread leg extending into the needle plate moves back and forth across the cutting edge 108 formed on the blade 110 of the control arm 88. Blade tip 1
Due to the frictional action of the thread against the thread 08, the thread is severed after several rotations of the bobbin. The free end of the needle thread is then pulled and discarded. As the bobbin rotates further, supplementary thread is wound onto it and can later be used as bobbin thread for lock stitching. The replenishment thread is bent downwardly from the path as shown in FIG. It is drawn into the bobbin through a passage between the arm 34 and the bobbin.

As previously mentioned, the fingers 90 are provided with edges 100 that are shaped to slow the movement of the thread along the fingers. As shown in FIG. 13, the finger includes a straight portion 112 and a concavely curved portion 114 extending smoothly from the straight portion 112 to approximately the tip 116 of the finger. The straight portion 112 curves the thread on the finger piece into a curved portion 114 having a predetermined curvature.
The curvature is such that the thread T is guided through the circular path 118 on the beak by the tip of the thread taker.
and the finger piece 9 from the axis of the thread taker under the support arm 33.
The fingers are predetermined to hold the thread until it is conveyed to the point of intersection with a line 120 drawn substantially perpendicular to a radius 122 extending to the tip of the thread. ing. The thread may therefore come off the finger too quickly and subsequently cross the top of the finger, as occurs in the case of a finger of the type described in U.S. Pat. No. 3,693,566. Movement outwardly and then inwardly across the support arm 32 and slot 94 is prevented and the thread is ensured to be guided into the slot. The curved portion 114 of the finger is preferably circular in shape, and as shown in FIG.
12. Forming the curved portion in a circular shape not only makes its operation more effective, but also allows it to be easily formed using common machining techniques.

The above description shows preferred embodiments of the present invention and is not intended to be construed as limiting. It should be understood that the present invention can be modified in various ways within the scope of the claims.

[Brief explanation of drawings]

FIG. 1 is a top view showing the thread taker in the sewing machine bed together with the bobbin case restraint device therein, in which the thread engaging finger according to the invention is positioned by the control arm during sewing machine operation; shows. Figure 2 is the first
FIG. 3 is a partially cutaway cross-sectional view taken along line 2-2 in FIG. 2 shows the needle thread ready to be wound onto the bobbin when captured by the device. Figures 4, 5, 6 and 7 are top views of the thread engaging fingers positioned for bobbin winding, with the thread take-up device in various positions during the initial stages of the bobbin winding operation; shows. Figure 8 is the 5th
9 is a cross-sectional view taken along line 8--8 of FIG. 7; FIG.
Figure 0 is an elevational view of the bobbin case, showing the needle thread in the thread tension device when the bobbin winding operation is performed. FIG. 11 is an exploded perspective view of the thread tension device; FIG. 12 is a cutaway view showing a part of the bobbin case, showing the function of the thread engaging fingers according to the present invention. FIG. 13 is an enlarged plan view of the fingers; FIG. 14 is a schematic diagram showing the shapes of the thread engaging fingers and the thread remover. 14...Thread thread taker, 22...Sword tip, 26...Bobbin case, 32...Thread tension device, 36...Thread tension spring, 72...Bobbin, 90...Finger piece, 94...
...Slot, 96...Shoulder, 100...Edge, 112...
Straight section, 114...curved section.

Claims (1)

[Claims] 1. In a lockstitch sewing machine, a thread thread taker is a cup-shaped thread thread taker that moves in a circular motion and has an axis and a peripheral rim on which a thread catching tip is formed, and a non-thread thread picker supported within the thread thread taker. A rotating bobbin case, a rotatable bobbin housed inside the bobbin case, and a needle that can perform longitudinal reciprocating motion and can be moved to a position to give a loop of needle thread to the thread catching tip for catching. and,
A thread tensioning device carried by the bobbin case and having an arm which together with the shoulder on the bobbin case forms a thread slot for the device, and one leg of the loop in which the needle thread is captured. a finger guiding into the slot and thence into a thread tension device; a thread capture groove extending from the outer periphery of the top flange of the bobbin to a hub extending between the top flange and the bottom flange of the bobbin; and a device for rotating the bobbin so that the thread passing through the thread tension device and extending onto the bobbin is caught on the bobbin with a thread catching groove and wound.
The slot communicates the inside of the bobbin case that houses the bobbin with the outer periphery of the bobbin case through which the needle thread slides during normal lockstitch operation, and the finger piece has a thread-engaging edge. has a circularly curved portion at the tip of the finger proximate to the slot, and has an introduction portion extending straight in contact with the curved portion, the introduction portion introduces the thread into the curved portion, and the thread is inserted into the curved portion. The curved portion holds the thread until the thread held at the tip crosses a line perpendicular to the radius extending from the axis of the threader to the tip of the finger piece;
Lockstitch sewing machine.